Dutch PHP Conference 2025 - Call For Papers

# Constantes pré-definidas

As constantes abaixo estão sempre disponíveis como parte do núcleo do PHP.

Constantes matemáticas
`M_PI` 3.14159265358979323846 Pi
`M_E` 2.7182818284590452354 e - número neperiano
`M_LOG2E` 1.4426950408889634074 logaritmo de e na base 2
`M_LOG10E` 0.43429448190325182765 logaritmo de e na base 10
`M_LN2` 0.69314718055994530942 logaritmo neperiano de 2
`M_LN10` 2.30258509299404568402 logaritmo neperiano de 10
`M_PI_2` 1.57079632679489661923 pi/2
`M_PI_4` 0.78539816339744830962 pi/4
`M_1_PI` 0.31830988618379067154 1/pi
`M_2_PI` 0.63661977236758134308 2/pi
`M_SQRTPI` 1.77245385090551602729 raiz(pi)
`M_2_SQRTPI` 1.12837916709551257390 2/raiz(pi)
`M_SQRT2` 1.41421356237309504880 raiz(2)
`M_SQRT3` 1.73205080756887729352 raiz(3)
`M_SQRT1_2` 0.70710678118654752440 1/raiz(2)
`M_LNPI` 1.14472988584940017414 logaritmo neperiano de pi
`M_EULER` 0.57721566490153286061 Constante de Euler
`PHP_ROUND_HALF_UP` 1 Arredonda 0.5 para cima
`PHP_ROUND_HALF_DOWN` 2 Arredonte 0.5 para baixo
`PHP_ROUND_HALF_EVEN` 3 Arredonda 0.5 para números pares
`PHP_ROUND_HALF_ODD` 4 Arredonda 0.5 para números ímpares
`NAN` NAN (como um float) Not A Number - um não-número
`INF` INF (como um float) Infinito

### User Contributed Notes 4 notes

39
md2perpe at gmail dot com
8 years ago
`I just learnt of INF today and found out that it can be used in comparisons: echo 5000 < INF ? 'yes' : 'no'; // outputs 'yes' echo INF < INF ? 'yes' : 'no'; // outputs 'no' echo INF <= INF ? 'yes' : 'no'; // outputs 'yes' echo INF == INF ? 'yes' : 'no'; // outputs 'yes'You can also take its negative: echo -INF < -5000 ? 'yes' : 'no'; // outputs 'yes'Division by INF is allowed: echo 1/INF; // outputs '0'`
18
Hayley Watson
12 years ago
`There are also the predefined PHP_INT_MAX and PHP_INT_SIZE constants, that describe the range of possible integer values.`
pemapmodder1970 at gmail dot com
8 years ago
`Although INF can be used for comparison against normal numbers and as a directed number, and behaves as reciprocal of zero, it is not like limit INF tends to infinity. These operations do not work:<?phpvar_dump(INF / INF); // float(NAN)var_dump(INF - INF); // float(NAN)?>However, it works with arc-tangent:<?phpvar_dump(atan(INF) / M_PI); // float(0.5)var_dump(atan2(INF, INF) / M_PI); // float(0.25)var_dump(atan2(1, INF) / M_PI); // float(0)?>`
Hayley Watson
7 years ago
`From PHP 7.2.0, the PHP_FLOAT_* constants are provided to describe the properties of floating point numbers that can be stored; PHP_FLOAT_MAX, for example, is analogous to PHP_INT_MAX and represents the largest possible floating-point number.`